The following is a transcript of a lecture by Kenneth Erickson, M.D., at a VEDA
conference held in Portland, Oregon.

Patients and families, of course, have known for a long time that vestibular
disorders bring about cognitive difficulties. Some psychologists and
neurologists here in Portland for at least five years, crystallizing in the last
two or three years, have now begun to recognize and study a number of cognitive
disturbances associated with vestibular disorders.

COGNITIVE DISTURBANCES

What is meant by cognitive disturbances?
Cognitive disturbances involve a difficulty in basic mental operations such as
memory, paying attention or focusing attention on something, and in prolonged
concentration. They also involve shifting attention from one subject or idea to
another. People with cognitive disturbances have trouble in perceiving accurate
spatial relationships between objects, in comprehending or expressing language,
and performing calculations, and in a number of other areas.

These are areas that psychologists routinely test when they are doing
so-called neuro-psychological exams.

A brief run-through of the kind of cognitive dysfunctions that we know of in
vestibular disorders would have to include the following areas:

First of all, vestibular patients exhibit a decreased ability to track two
processes at once, something we usually take for granted.

This ability requires a rapid shifting of attention. A good example is when
you are driving and you have one person approaching unexpectedly coming out of a
left-hand lane and another car coming behind you unexpectedly on your right
side. Suddenly there are two things that you need to monitor and pay attention
to at the same time. This might have come easily to you at one time, but if you
now have vestibular difficulties, it's very hard.

Another example is when you have conflicting emotions inside of you, if, for
example, there are two different things you want to do at the same time. The
sensation you feel is confusion. Because of your cognitive problems, you may
find it very difficult to express that confusion.

These are only two concrete examples of a pervasive problem.

The second area of cognitive problems vestibular patients exhibit is
difficulty in handling sequences. This includes a wide range of sequences. It
pertains to the mixing up of words and syllables when you're speaking, to the
transposing or reversing of letters or numbers, to having trouble tracking the
flow of a normal conversation or the sequence of events in a story or article.
All of those have been very frequent complaints of the vestibular patients that
we see.

A third area would be decreased mental stamina. That speaks for itself. For a
vestibular patient an hour or two of concentration is a special blessing, and
most days 15 minutes of intellectual concentration is very fatiguing.

The fourth area involves decreased memory retrieval ability, the ability to
pull out information from your long-term memory store reliably. You might hit it
most of the time, but you do not have a reliable rate.
Number five is a decreased sense of internal certainty. This is a peculiar way
to state it, but it is exceedingly accurate. Vestibular patients with on-going
physical problems have a frustrating lack of closure. They lack that
"ah-ha; I've got it now; I see the big picture." Or "that's what
I was trying to remember; I know it's that." They lack that kind of
certainty which measures an idea or a conversation or a social situation up
against some internal "gold standard." Vestibular patients often lack
internal certainty.

Finally, people with vestibular disorders experience a decreased ability to
grasp the large whole concept. The ability to see the big picture or the forest
for the trees is very elusive for someone with vestibular disorders.

MEMORY PROBLEMS

I'd like to discuss these areas but most specifically memory problems in
vestibular disorders; for most people that I see the memory problem is the most
pervasive and troubling one.

To begin with I'd like to address what is known about stages of memory.

Using human and animal studies, scientists have found out that there are
varying distinct stages of memory, and these are tied in with distinct physical
areas of the brain.

(We'll ignore sensory memory.)

Immediate memory is where I'd like to begin. This is the ability to hold a
name or phone number in mind for up to 30 seconds and sort of juggle it around
while you're walking over to the telephone. This kind of memory takes
concentration, and if any of us, sick or well, are suddenly distracted by a
small child or something, it may be gone. It is a very fragile store of memory,
about 30 seconds long. If the phone number stays longer after distraction,
that's because it's gotten into recent memory.

The recent memory area has to do with taking new information and recruiting
it into long-term memory. This is a key area that many vestibular patients
complain of.

Recent memory can be sub-grouped into declarative memory, which refers to
information -- the sort of thing you'd pick up in a textbook or an article or a
conversation -- and procedural memory, which refers to procedures -- how to do
something. A number of vestibular patients have noted that procedures tend to
come easier than pulling out facts. Thus if there's a logical sequence that they
are familiar with from before their injury, and they can fit the new information
into that sequence, they have less difficulty than with placing new
non-sequential information into their memories.

These kinds of memory are located in different areas of the brain, just as
are the immediate memory and the sensory memory.

Finally if you're successful, the long-term memory store is filled with the
information you want and can remember. It goes into what is called remote
memory, and that store of information and sequences is diffused throughout the
brain.
The areas of the brain which are keys to memory are the temporal and frontal.

If we look at microscopic sections of the brain, we see our brain cells are
tied together with an enormous amount of interconnections. This is particularly
true in areas that are called "association areas."

That's a handy name because to remember things you have to form associations
and pull them out by associations, and throughout the front part of the brain,
throughout areas that are called tertiary in other parts of the brain, you have
an enormous mass of interconnections between the brain cells.

Some brain cells have 100,000 connections to other brain cells. It's no
wonder that we can store an enormous amount of information; some scientists
think it may be limitless.

When we take a look in the deep areas of the brain, as though it were sliced
in half, there are some structures that are very relevant to what I was just
speaking about.

Immediate memory involves a part of the cortex that is traveling between
where you hear and process your hearing and the front part of the brain where
you speak. It's a kind of traveling loop from the hearing processing center, the
auditory area, around through some fibers to the speaking area, (Broca's area).
It is this area where strokes can impair the immediate memory ability enormously
and very specifically. In some stroke victims, just that kind of memory gets
affected.

Going on, recent memory, the one that allows us to store information for a
long period of time, is housed in a couple of areas. It requires the ability to
input the information, which is very much a frontal-lobe function connecting
into deep structures.

Then there's a complex loop, that's been studied now for 45 to 50 years that
allows memories to cement down over minutes to months. The hippocampus, the long
banana-shaped organ on both sides is the key area that allows us to fix the
information over weeks and months.

If there are strokes or other damage in this area, a person becomes virtually
locked in time. They do not pick up any new information. They might sound very
intelligent based on their old information, from before the stroke -- that's
still there for them. They might sound very intelligent in terms of something
you are just saying to them this instant, but if you ask them what we were
talking about five minutes ago, or half an hour ago, that information is gone.

Now we speculate that this area, this entire area, is somehow affected in
people with vestibular disorders because recent memory ability, the laying down
of new information is very confounded and difficult, in comparison to their
pre-accident or pre-surgery history.

Let's talk a few minutes about stages of information input and retrieval.

The input stage is called acquisition; you're acquiring information. The
storage stage is called retention, the ability to retain over minutes or months
or years. And the retrieval, the output stage, is called retrieval. The
acquisition and retrieval stages I mentioned in this diagram involve the front
part of that loop. They are very much a front executive function of the brain.

The whole frontal lobe of our brain is involved in all our planning, decision
making, handling two things at the same time, problem solving, sticking to a
task, mental stamina -- a lot of those things sound very similar to the areas I
was pinpointing for vestibular disorders.

We don't understand how the vestibular apparatus links in so intimately with
the frontal lobe in terms of the mental processes we see impaired. That is an
unknown. It will be a very difficult area to study based on our present
knowledge. It is potentially a fruitful area to study over future years,
however. In any event, the key problems in vestibular recall are the input and
the output. I say this because the storage part, the retention part, is actually
not so badly affected.

We know this because we are able to measure the storage component. You might
call it the tape recorder. Memory retention involves the temporal lobe and can
be measured by using so-called recognition tasks. In recognition tasks, the
patient is simply asked, "have you seen this word in the last half hour or
not?" Patients are given virtually everything but the answer. It's like a
multiple-choice question.

With that level of assistance, people with vestibular disorders do
exceedingly well. It is also frustratingly well because on standard
psychological tests, a vestibular patient can look darn good. This adds to their
feeling of invalidation. Doing well on those recognition tasks can make the
patient and sometimes the examiner believe that the physical and chemical
malfunction is all psychosomatic or hysterical.

But if the examiner takes it a step further and asks how good is a person at
putting in the information and then without much help pulling it out (much more
like real life), that's when we see significant problems.

SPECIAL TERMS

I've coined a few terms to discuss the problems that arise when specific
kinds of tests are given to vestibular patients.

First of all, we find in the clinic that vestibular patients have a reduced
channel capacity.

We all have a certain capacity to take in new information at a certain rate;
we get used to being able to do and to do it at our own rate. We know when we
are tired we'll be a little more poor at it, or when several things are coming
at us at once it will be reduced, but we know what it feels like, and we're
pretty comfortable with our rate. It's similar to a computer's capacity to
process information at a certain speed.

This capacity is considerably reduced in the majority of patients we see in
the clinic with vestibular disorders.

Another area bears on the sequencing of information. The ability to recall in
what order we learned or heard or were exposed to information is crucial to
later recalling it in a meaningful or useful way.

For reasons we don't fully understand, most vestibular patients find it very
difficult to properly sequence information.

If they're presented with a task, like the one we use in our clinic to
measure sequencing, the "divided attention recall test," where we
break up the person's attention, we find our patients have real difficulty. This
task is much more like real life than mere recognition tasks. We present a
series of words to the person and, not only do they have to pull back the word
that they saw a couple of words ago (so they're starting to have to reach back),
but at the same time they're having to sort every new word into a category. So
there's two different things going on at once, and they're also having to reach
back and recall recent material.

How many of you with vestibular problems find it hard to track a
conversation, especially if there's more than one person you're listening to
converse? You find that it's real fuzzy trying to reach back and see where it
was just going, much less the big task of tracking what's going on right now.

I would imagine that the majority of you have had that experience. Even
extremely bright people who have vestibular problems have massive problems with
this. It's also extremely fatiguing.

Thus the sequencing problem that shows up in tasks like this is unique. They
can reach back, the people who have taken this test, and hold back some of that
information, but they often reach back too far or too recently; it's as though
the time tag, the ability to know just about when that word happened, is very
loose or gone. We don't understand it, but it's exceedingly similar to a kind of
problem seen in early Alzheimer's disease. It seems to indicate a loss of a kind
of time setting or time tag.

Finally, the lack of internal conceptual validation, the "aha, I've got
it" experience, the sense of being valid about what you're thinking, seeing
the big picture, being sure you've accurately completed a detailed task, being
certain you remembered the correct name or fact, having that satisfying feeling
of "yep, that's the match," -- is frequently gone.

Even though the majority of people we test are darn smart in many ways, they
lack this sense of rightness. The vestibular patients we see often do rather
well on the standard kinds of psychological tests, but we find they have a real
problem knowing they are right, inside. They may be right 90% of the time, but
they don't have that internal satisfying feeling.

That's a difficult one to understand, but we know from studies done years ago
of people with brain injury that deep areas in the front part of the brain from
the deep thalamus out to the front part of the brain are very important for
locking into a kind of "gold standard," matching your sense with what
is somehow stored in the brain and knowing that you are right.

Again, it raises fascinating questions about is there some way when you're
very young that the vestibular system is wired into this whole area. We have
absolutely no way of knowing that at this time. We do know the vestibular system
links with your visual system, and visual control is very much a frontal lobe
function, but there is no real knowledge of other networks going into
these memory centers.

PRACTICAL RAMIFICATIONS

What are the practical ramifications of all these deficits that I've been
describing?

The three areas of dysfunction I just listed -- the decreased channel
capacity, the diminished sequencing ability, and that lack of the aha experience
inside -- those three areas cause incredible difficulties with simple daily life
functions.

There's an astonishing contrast between the ease which most of our patients
remember encountering in social situations prior to their illness compared to
the difficulty they feel now when they try to deal with more than one person at
a time. Situations which seemed hum-drum when they were well now appear
impossible.

Occupationally, any time-locked task that has to be done by a certain time
obviously is going to be affected. We don't even have to go into the detail I've
gone into to say that the fatigue that is felt causes great problems with those
kind of tasks. But any task that requires tracking more than one train of
thought at a time, like that of a receptionist answering phone calls and
plugging them into the right message boxes and so forth would be dramatically
impaired.

Finally psychiatric complications such as depression and anxiety are almost
too obvious to mention. After this kind of alteration of your most basic habits
of thought, it's hard to conceive of not experiencing anxiety, depression, and
disappointment with yourself.

Even if you have a supportive family structure that understands the cognitive
problems, you end up inside not getting that sense of satisfying "I'm doing
what I should be doing."

That links with that certainty inside that I spoke about. Even when you're
fatigued and vestibular and you know you put in a good day and have done the
best you can, that internal lock that says "I know I did this, I can
retrieve what I did today, I can look at the big picture, and I had a good
day" is not there for most vestibular patients. That alone, even within a
loving supportive family and with no financial problems, would create anxiety
and depression.

PHYSICAL AND PSYCHOLOGICAL RELATIONSHIPS

Why do these kind of memory and functioning patterns exist among
vestibular patients?
There are three very obvious factors that many psychologists will raise. Those
of you who have seen psychologists may recognize these diagnoses. First, pain is
bound to cause problems with concentration and depression. Second, anybody with
as much fatigue as the vestibular patient experiences will have a lot of
trouble. Finally, the depression ensuing from that and everything else affects
people's attention span and concentration and memory.

So, those of you who have gone through psychological tests often end up with
a psychologist telling you that you have a few problems with attention but
you're above average IQ, and there's nothing much to worry about; in fact, on
their tests you look pretty darn good. The things that they do see, the mild
attention and concentration problems, are probably due to the pain, the fatigue,
and the depression.

Well, the hypotheses that we have are somewhat different than that. We don't
know that ours are correct, but they do not include the above. The reason that
we don't explain the difficulty vestibular patients have as due to pain, fatigue
and depression is that if you test people with pain, with fatigue and
depression, they either don't have this pattern of difficulty or it's far
milder.

If we test people with a lot of pain or depression or fatigue, they will do
badly on a variety of attention and concentration tests. On those tests,
however, vestibular patients may do pretty well. If, instead, we test using the
tasks where we divide up the patient's attention between sorting words by
category and pulling back recent words, we find that even when they're feeling
stable and are not in much pain, on this one test vestibular patients perform
badly.

Obviously common sense leads us to explore this further. We can only conclude
that this kind of malfunction seems highly specific to most vestibular patients.
Shortly we will have enough control patients to publish these findings.

Our hypothesis is that the reason you have this problem as a vestibular
patient is that your brain stem is affected. The brain stem is a stalk connected
to the spinal cord. There are nuclei located in the brain stem that attach to
your balance system; they are also highly important for keeping your cortex,
your thinking areas, alert and aroused and attentive.

Could it be that since you're constantly fighting the mismatch from your
visual input and your disordered balance system that a very basic mechanism -- a
mechanism that was developed as you learned to sit and crawl and that influenced
how you later manipulated objects and then walked and spoke and thought, a
mechanism that's taken for granted and built into very fundamental habits --
could it be that something that fundamental is being distorted? That the
vestibular and visual disturbance interferes with nuclei functioning within the
brain stem and thus interferes with your sequencing of information and impairs
and reduces your channeling capacity?

It's an intriguing hypothesis, exceedingly difficult to test. Nevertheless it
makes some sense, as anyone with a vestibular disorder can speak to. Basic
problems with reading, watching letters transpose, problems with movement and
the orienting to the environment -- these are manipulations of the environment
that were learned at a very fundamental developmental stage.

Question: Can some of these problems be described as dyslexia?
Answer: Yes, these symptoms can be misunderstood as dyslexia, although dyslexia
has some other components to it.

Question: Is this damage permanent? Will the brain cells die from not being
used?
Answer: We have no way of finding out the physical damage. The MRI's (Magnetic
Resonance Imaging scans) often look perfect. It's likely that your vestibular
system is sending inaccurate information to other brain areas that don't know
how to handle it and/or information that gets distorted at very elementary
levels of functioning. Those basic functioning areas seem to need accurate
information from the vestibular system to think.

TREATMENT

Can we fix it? That is a very complex question but obviously among the most
important questions to ask. Our clinic, which has been doing some of these
studies, is very dedicated to trying to improve these memory problems. We're up
against the fatigue problem, which we can do little
about.

One of our goals is to try to teach people tricks or handy ways of
remembering things that would help anybody walking around the streets, shorthand
ways of remembering things using pictures and so forth.

We've discovered if the picture is highly dramatic and a movement-filled
picture, patients become highly vestibular, and it interferes with the memory.
So we have to train people to remove a lot of motion from their images. These
tricks are one aspect of our work. Using them, we have seen some improvement,
but not without effort and time and learning to make these strategies become
automatic.

Increasing patients' stamina, allowing them to take in larger amounts of
information is an area which we're highly interested in pushing. A couple of our
patients have been able to move into that phase, and we see that slowly, again
not without a lot of effort, the capacity to increase the amount is there. I
have a guess that part of the reason for that improvement is that one is
learning new habits -- is training him- or herself to think again. As a
vestibular patient, you must learn to move around in a slightly different-sized
intellectual room. As you learn, just as in physical vestibular therapy,
compensating becomes automatic. You become comfortable with that little basic
mental operation and this one, and you don't have to be thinking consciously
about every step.

These new automatic habits allow you to take in more.

Our goal is to train these habits so people can actually improve on their
performance and feel the difference at home. Again it's confounded by the
fluctuating symptoms of the vestibular condition, by depression, by stress, by
all kinds of other things that enter into your memory and finally by the fatigue
that is constantly there because of the mismatch of your vision and your balance
system.

Nevertheless, those who have reached that stage do feel a sense of
gratification, and that drives us on. Our own sense here in the clinic is that
given enough time, people will develop these new habits. We hope that we're
developing a mental operation therapy similar to the physical vestibular
therapy. Because it's so much more subtle and abstract, we suspect it will be
very slow going. We feel that the rewards are there, and we continue to be
dedicated to exploring them.

THE FUTURE

To go on, then, after completing the initial study that I mentioned on the
divided attention/recall test, we plan to do two studies in which we look at the
channel capacity, the limit on taking on new information before suddenly the
slate is wiped clean and none of it comes back.

We are asking what is the sequencing problem when it comes to memory. How can
we get around it? How can we understand it? Can we actually find some
interesting little patterns that might help compensate for its dysfunction?

Finally, later on, we hope to study this very intriguing difficulty with that
sense of closure, of certainty, inside. I suspect it's a multi-faceted
experience that requires five or six different things to come together.

Within all this, of course, we have to include studies of people with pain,
but no vestibular problems, depression but no vestibular problems, fatigue and
no vestibular problems, head injury and no vestibular problems. That allows us
to control for some of those confounding variables that people now use to
explain the problem.

QUESTIONS, ANSWERS

Question: Do other people have problems with getting the first part of a
word and then losing the second part, or getting the first part of a sentence
and losing the second part?
Answer: These are indeed very common difficulties among vestibular patients.

Question: What effects might medicine have?
Answer: Many of the medications for vestibular problems are sedatives, even the
anti-histamines and pain medications have a sedating effect. These will have an
effect on memory and concentration. Vestibular patients who need medication to
control their symptoms are often caught between a rock and hard place -- the
vestibular symptoms cause them cognitive difficulties, but if they medicate to
control the symptoms, the medication causes cognitive problems.

Question: I have a problem with getting the general idea of articles when I'm
reading. Is this common?
Answer: Definitely. In our clinic, we work on sequence and memory aids, in order
to break the material down into simpler steps -- breaking an article, say, into
key points. If there are more than five or six, then you will have trouble. Even
simple articles can seem very complex. You can break reading materials down into
key points, but it's hard work. You need to pick things that are worth it to
you. Otherwise you'll get too fatigued and discouraged.

Question: Why do we mis-read, even when we know we are misreading?
Answer: It's called a substitute syndrome. Vestibular patients experience the
syndrome often; it's very frustrating. I don't know why it's so rampant in
vestibular patients. Probably it's linked to underlying injury to the vestibular
system that goes beyond the vertigo, etc. When we tested a patient who was no
longer having vertigo and whose scores were rather impressive in other areas,
this "mis-reading" syndrome still existed. We don't know why. We ask,
is the perilymph fistula creating a direct problem different from the vertigo?
We need a larger sample and controls to really say.

Question: Do you have any help for family members?
Answer: A vestibular dysfunction affects the whole family because it affects the
patient's total life. Family members need help and understanding almost as much
as the patient him- or herself. In the clinic, we include family members'
perspectives because they can sometimes give clues to behavior that patients
aren't aware of. We also do counseling with family members.